1. Field of the Invention
This invention relates to a rolling mill system having a capability of crossing, bending, offsetting and axially shifting the work rolls of the mill in order to reduce edge drop of a rolled metal workpiece (herein called strip), to increase strip crown control range, to reduce localized roll wear, and to improve strip surface quality.
2. Description of the Prior Art
Each of the roll-affecting functions above described is individually known to the prior art.
For example, shifting the work rolls in an axial direction for improved roll wear and enhanced strip properties, is shown in U.S. Pat. No. 4,898,014 which provides hydraulic cylinders disposed at the ends of the work rolls to shift those rolls axially, and a number of roll bending cylinders acting on the roll chocks to distribute the total roll bending force at the center of the roll chocks throughout the roll shifting range.
Roll crossing is exemplified by U.S. Pat. No. 4,453,393 which embodies paired roll crossing, i.e. the crossing of both work rolls and backup rolls in which housing-mounted jacks and associated brackets exert forces on a roll bearing case, and through it, on a roll chock to effect roll crossing. Japanese patent documents 52-77526; 52-77527; 53-127353; 62-26304, and European Patent Application No. 0 553 480 A3 show various other systems for roll crossing.
Combined roll crossing and shifting is described, for example, in U.S. Pat. No. 5,655,398 which provides, in addition to axial shifting cylinders at the ends of the respective work rolls, inclined surfaces on the roll chocks which, on shifting of the rolls, causes the rolls to cross. European Patent Application No. 0 506 138 A1 also shows roll crossing and shifting wherein hydraulic jacks exert forces on the roll chocks in the direction of rolling to cause work roll crossing, and wherein additional hydraulic cylinders are disposed at the ends of the respective work rolls and bear on the roll chocks in an axial direction to cause roll shifting. A similar construction for roll crossing and shifting also is shown in Japanese patent document 70-60310.
Japanese patent document 61-259812 discloses apparatus for roll shifting, offsetting and crossing wherein there is provided a first pair of inclined surfaced wedge members movable in a strip rolling direction, and a second pair of wedge members mounted on a common member with the roll chock and movable in the roll axial direction and slidable against the first wedge members, so that the work rolls may be shifted axially, offset and crossed.